Abstract
Trichoderma reesei is one of the most important industrial filamentous fungi that produce large amounts of extracellular enzymes. β-Glucanase is used widely in biofuels, food, and animal feed. Here, a higher β-glucanase activity mutant was obtained from T. reesei via atmospheric and room temperature plasma (ARTP) mutagenesis. Compared with that of the original strain, the β-glucanase activity of the mutant ARTP-9 increased by 56.23%, reaching 45.12 U/mL and its enzymatic activity demonstrated transgenerational stability. Compared with the original strain, transcriptome sequencing revealed 1793 differentially expressed genes (DEGs), of which 640 were upregulated and 1153 were downregulated. Gene Ontology (GO) enrichment analysis revealed that the DEGs were significantly enriched in functional categories related to the cell membrane, cofactors, and carbohydrate energy metabolism. In KEGG metabolic pathway analysis, 278 KEGG pathways were identified, which were enriched mainly in the biosynthesis, carbon metabolism, and amino acid metabolism of secondary metabolites. The results revealed that the enhanced β-glucanase activity in the mutant is likely linked to both the upregulated expression of several genes, including those encoding hemicellulose hydrolases, trehalase, γ-aminobutyrate aminotransferase, and phosphoenolpyruvate carboxykinase, and increased levels of metabolites, such as palmitic acid and linolenate.